Effects of complex spa therapy, which comprises swimming training in a hot spring pool, inhalation of iodine salt solution and fango therapy, were analyzed in patients with steroid-dependent intractable asthma (SDIA) by comparison between the subjects with and without efficacy of the therapy. 1. The complex spa therapy was effective in the patients with lower levels of FEV(1.0%) and % PEFR. 2. The complex spa therapy was not always effective in the patients with a low value of % V(25), which represents depressed airflow in the small airways. 3. The efficacy of the complex spa therapy was found in the patients showing a low value of % V(25) accompanied by BAL neutrophilia, but not found in those without increased proportion (more than 10% ) of neutrophils in BAL fluid. The results reveal that the complex spa therapy is effective in patients with SDIA showing low values of FEV(1.0%) and % PEFR, and in those with a low value of % V(25) and BAL neutrophilia.